This invention relates to a semiconductor manufacturing method and apparatus with a conveying system, for automatically conveying a substrate such as a wafer or a glass plate (hereinafter, xe2x80x9cwaferxe2x80x9d) or a photomask or a reticle, or a pod for accommodating such a substrate, for performing an exposure process, a washing process and an inspection process, for example.
Referring now to FIG. 8, wafer conveyance in a semiconductor manufacturing apparatus (here, an exposure apparatus) will be described.
In an exposure apparatus such as shown in FIG. 8, plural substrates 4 are accommodated in a carrier 2, and they are sequentially taken out of the carrier by a conveying robot 1. Each substrate is then loaded onto a mechanical prealignment station 39, and wafer alignment is performed in relation to the position of an orientation flat 4a defined at an edge of each substrate 4. In this positioning process, first the substrate 4 is held by a mechanical alignment chuck 8, and then, while rotating the substrate 4 by a mechanical prealignment xcex8 stage 7, the position of the orientation flat 4a of the substrate 4 is detected by using a mechanical prealignment optical system (9, 10 and 11). Then, the position of the orientation flat 4a as well as the amount of eccentricity of the substrate 4 are calculated, and finally, the substrate is positioned into a predetermined position, by use of a mechanical prealignment X stage 5, a mechanical prealignment Y stage 6 and the prealignment xcex8 stage 7. Thereafter, the substrate 4 is gripped by a substrate holding means (hand), not shown, and it is moved onto a wafer chuck 12. Subsequently, the substrate 4 being chucked by the wafer chuck 12 is moved stepwise by means of a processing station 13, and an exposure process is performed thereto through an optical system, not shown. After completion of the exposure process, the substrate 4 is unloaded from the wafer chuck 12 by the conveyance robot 1, and it is stored into a carrier 3.
Conventionally, carriers each for accommodating plural substrates therein are an open type carrier (open type cassette) wherein the carrier is loaded into a semiconductor manufacturing apparatus without being kept in a clean box and wherein the carrier has no container for isolating each substrate from an outside ambience. Such an open type cassette may not cause particular inconveniences as long as the entire space inside a clean room is kept as an environment containing only a few particles. However, if there are many particles contained, it causes a problem that particles are adhered to the substrate.
As a matter of course, it takes much cost to keep the entire space of a clean room as an environment having a few particles, for particle deposition prevention.
In consideration of it, a method for keeping each substrate in a clean state regardless of the presence of some particles in a clean room, has been proposed. This method is called a mini-environment system. According to this system, a carrier as a whole, containing substrates therein, is covered by a container. When the carrier is loaded into a semiconductor manufacturing apparatus, a door of the container is opened such that the inside of the container and the internal structure of the semiconductor manufacturing apparatus are coupled with each other through the opening of the container. With this arrangement, even if there are some particles in the clean room, particles are not deposited on a substrate being kept isolated by the container.
As regards this mini-environment system, there are two types proposed. Theses two types are categorized in terms of the door opening/closing direction. The first one is a type wherein a front door is opened/closed along a lateral direction, and this type of cassette is called a front open unified pod (FOUP) being standardized with respect to a 300 mm substrate in accordance with the SEMI standard. The second type is one called a bottom opening type wherein a bottom door is opened downwardly. A standard mechanical interface pod (SMIFPOD) is an example of this type.
On the other hand, semiconductor manufacturing apparatuses should have measures for prevention of outward leakage of electromagnetic waves. According to regulations for electromagnetic wave leakage prevention, each semiconductor manufacturing apparatus must satisfy a limitation for an electromagnetic wave interference characteristic (electromagnetic radiation interference). An example of such regulations is found in the European harmful electromagnetic wave restrictions (CISPR Pub. 11).
Generally, a main assembly of a semiconductor manufacturing apparatus is housed in a metal chamber, to prevent outward leakage of electromagnetic waves. However, a resin such as an acrylic resin is used in a portion through which the inside of the semiconductor manufacturing apparatus is to be observed. In consideration of possible leakage of electromagnetic waves therethrough, conventionally, a metal mesh is mounted thereat to shield the electromagnetic waves. Since the mesh metal member does not shield electromagnetic waves if it is not grounded, usually the metal member is kept electrically communicated with the chamber so that it is grounded.
When a mini-environment type pod such as a FOUP or SMIFPOD as described above is used in a semiconductor manufacturing apparatus, there arise inconveniences such as follows.
Since, in conventional semiconductor manufacturing apparatuses, an open type cassette is loaded into the apparatus when the same is used, the provision of a function for electromagnetic wave leakage prevention only at the semiconductor manufacturing apparatus itself is sufficient. According to a pod of a FOUP or SMIFPOD type, on the other hand, a pod is mounted outside the semiconductor manufacturing apparatus. Also, a door at the front or bottom of the pod is opened in response to the opening of a door at the semiconductor manufacturing apparatus side, and a substrate kept in the pod is taken out. Usually, the front or bottom door of the pod and the door at the semiconductor manufacturing apparatus are held open during the operation of the semiconductor manufacturing apparatus. Thus, the container of the pod just serves as a portion of an outside wall of the semiconductor manufacturing apparatus. As a result, even if a metal mesh member is used in the semiconductor manufacturing apparatus for prevention of electromagnetic wave leakage, there is a possibility of leakage of electromagnetic waves through the container unless the container is equipped with a function for electromagnetic wave leakage prevention.
It is an object of the present invention to provide a semiconductor manufacturing apparatus having a function for preventing outward leakage of electromagnetic waves through an opening.
It is another object of the present invention to provide a pod mounting method effective to prevent outward leakage of electromagnetic waves.
In accordance with an aspect of the present invention, there is provided a semiconductor manufacturing apparatus, characterized by leakage preventing means for preventing outward leakage of electromagnetic waves through an opening defined when a pod having a substrate accommodated therein is mounted on the semiconductor manufacturing apparatus, wherein said leakage preventing means is provided at the semiconductor manufacturing apparatus side.
In one preferred form of this aspect of the present invention, said leakage preventing means includes at least one electromagnetic wave shielding plate provided at the semiconductor manufacturing apparatus side. The pod may be a mini-environment type pod. The pod may be one of a front-open unified type pod and a standard mechanical interface pod. The at least one electromagnetic wave shielding plate may be arranged to surround the pod as the same is mounted. A first electromagnetic wave shielding plate may be openable and closable so that an opening defined when a carrier in the standard mechanical interface pod is moved downwardly is closed by said plate. There may be a second electromagnetic wave shielding plate in addition to the first electromagnetic wave shielding plate, said second electromagnetic wave shielding plate having an openable and closable slit and being provided between an indexer for moving the carrier in the standard mechanical interface pod downwardly and a conveyance robot for conveying the substrate.
The apparatus may further comprise an electromagnetic wave shielding member provided on at least one of an inside wall face and an outside wall face of said electromagnetic wave shielding plate, or inside said electromagnetic wave shielding plate. The electromagnetic wave shielding member may be provided at a surface of said electromagnetic wave shielding plate, which surface is engageable with a chamber for surrounding a main assembly of said semiconductor manufacturing apparatus when said electromagnetic wave shielding plate is closed.
The electromagnetic wave shielding member may comprise a mesh-like metal. The electromagnetic wave shielding member may comprise a metal coating. The leakage prevention by said leakage preventing means may be arranged to provide a limit value not greater than 100 dB (xcexcV) with respect to a frequency range of 9 KHz to 400 GHz. The electromagnetic wave shielding plate may be grounded through the chamber. The semiconductor manufacturing apparatus may be an exposure apparatus.
In accordance with another aspect of the present invention, there is provided a pod mounting method, characterized by leakage prevention for preventing outward leakage of electromagnetic waves through an opening defined when a pod having a substrate accommodated therein is mounted on a semiconductor manufacturing apparatus, wherein the leakage prevention is accomplished at the semiconductor manufacturing apparatus side.
In accordance with a further aspect of the present invention, there is provided a semiconductor device manufacturing method, including a process for producing a semiconductor device by use of a semiconductor manufacturing apparatus as recited above.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.